Fire control mechanisms and actions for modern auto-loading firearms are generally highly-engineered mechanical devices that are designed with tight spacings/tolerances, and necessarily must operate reliably for a high number of firing cycles. For example, automatic and/or semi-automatic firearms, such as M16/AR15, M4, and AK-47 auto-loading rifles generally are required to fire thousands of rounds, especially for military uses such as under battlefield conditions, without failure. During firing of such auto-loading firearms, as the spent casing is ejected, a new round of ammunition will be received from a magazine and loaded into the chamber of the firearm. As the bolt is moved forward and pushes the round of ammunition into the chamber, the bolt generally undergoes a partial rotation so as to engage a series of locking lugs with a series of barrel lugs, thereby locking the bolt into position and sealing the round of ammunition within the chamber.
Feed ramps generally are used to guide the rounds of ammunition from the magazine into the chamber, and are typically machined into the material of the barrel or barrel extension that surrounds the breech opening, such as by enlarging or expanding one or more of the gaps that separate the barrel lugs, and, in rifles such as the M4, can extend into/be matched with feed ramps formed in the upper receiver. During a loading operation, the ammunition cartridges rub against the feed ramp, causing peening, galling or wear of the feed ramp surfaces, especially tamp surfaces formed in the receiver, which typically can be formed from metals such as aluminum that provide a reduction in weight but have lower impact toughness than steel or similar materials. Dirt and debris further can be trapped at the feed ramp surfaces, causing additional or faster wearing of the ramp surfaces, and/or leading to jams or failure of the feed ramp. Thus, polishing and repair of feed ramps can be required on a frequent basis to maintain such auto-loading firearms. Additionally, it is becoming increasingly popular for many firearms, in particular for military or tactical uses, to be modifiable to the different types of ammunition, and thus, it is necessary that the surfaces of the feed ramps be able to accommodate the use of such ammunition.
Accordingly, there exists a need for an improved feed ramp system for directing cartridges into a chamber of the firearm that provides for a reduction in wear and galling on the interior surfaces thereof. It is to the provision of a solution to this and other problems that the present disclosure is primarily directed.